Strand annealers



Jan. 25, 1966 E, A. TAYLOR, JR 3,230,637

STRAND ANNEALERS Filed 001;. 16. 1961 SECOND] T I I H|RD| T GE STAGE {STAGE I I ...gm%

A TORNEY INVENTOR.

ERNEST A. TAYLOR, JR.

United States Patent 3,230,637 STRAND ANNEALERS Ernest A. Taylor, Jr., Decatur, Ala., assignor, by rnesne assignments, to Monsanto Company, a corporation of Delaware Filed Oct. 16, 1961, Ser. No. 145,180 1 Claim. (Cl. 34-156) This invention relates to strand annealers and more particularly to apparatus for annealing a continuous tow of thermoplastic material.

One of the disadvantages of conventional tow or filament annealing processes is that these processes must be carried out in batch form. The material to be annealed is stored in an autoclave and is then subjected alternately to vacuum and steam under pressure. This process is obviously time consuming. Continuous annealing appa ratus used in the past has been subject to the disadvantage of steam leakage. Various seals have been used to prevent leakage of steam from the apparatus. However, these seals have in general been ineffective-as well as requiring almost constant maintenance.

It is desirable in some instances to anneal and shrink thermoplastic filament-s or yarns. This is especially true where a fabric of thermoplastic material is to be molded into a particular shape or configuration. Obviously, the more a yarn or fabric of thermoplastic material is allowed to shrink, the more it can be stretched in a subsequent molding process. With this in mind, one of the objects of this invention is to provide an apparatus for annealing a strand.

Another object of this invention is to provide an apparatus for continuously annealing a strand at substantially atmospheric pressure.

Another object of this invention is to provide an apparatus for annealing and allowing shrinkage in a continuous tow of thermoplastic material.

A further object of this invention is to provide an apparatus for continuously annealing a continuous strand without the use of complicated and inefiective seals.

Still another object of the present invention is to pro vide a tow annealing apparatus having separate stages for heating and advancing the tow.

A still further object of this invention is to provide an apparatus for heating and shrinking a bundle of thermoplastic filaments.

One embodiment of the present invention contemplates a continuous tow annealer having a first stage wherein heated air is alternately directed against opposite sides of the tow to flow through and completely anneal the tow. Air flows from the first stage through a second stage to lift and advance the tow to a third stage where relaxation of the filaments in the tow is completed as the air is separated from the tow. The tow is heated and annealed in the first stage. Since the tow is moved through the apparatus by the flow of air, rather than by positively driven rolls, the tow has ample opportunity to completely relax and to shrink to the theoretical maximum.

Other objects and advantages of the invention will become apparent when the following detailed description is read in conjunction with the drawing, in which FIGURE 1 is a perspective view of one embodiment of the invention showing the general arrangement of the apparatus,

FIGURE 2 is an enlarged vertical sectional view taken on line 22 of FIGURE 1 showing the arrangement of bafiles in the treating chamber, and

FIGURE 3 is an enlarged perspective view of the lower portion of the annealing chamber showing the construction of the various ducts therein.

Referring now in detail to the drawing, a plurality of rolls 10 and 11 are shown advancing a porous tow 12 along a path, the tow being a bundle of filaments. A treating chamber 13 having an upper chamber section 14 and a lower chamber section 15 is provided for annealing the tow 12. The lower section 15 is positioned beneath the tow 12 while the upper section 14 is positioned above the tow 12, as illustrated in the drawing. In a first stage of the chamber 13 hot air enters through ducts 18 and 19 and is directed upward against the tow 12 through ducts 22, 23 and 24 and downward against the tow through ducts 22a, 23a, and 24a displaced along the tow 12 from the ducts 22, 23 and 24 so that heated air is alternately directed against the upper and lower surfaces of the moving tow 12. This insures that the heated air completely penetrates and anneal's all of the filaments in the tow 12. All of the ducts 22, 22a, 23, 23a, 24 and 24a are positioned at acute angles to the path of the tow so that air flowing from these ducts urges the tow along its path.

So that the air streams will pass through the tow 12, exhaust ducts 25, 26, 27 and 28 are provided for carrying the heated air from the ducts 22, 22a, 23 and 23a directly from the first stage to the third stage. The exhaust ducts 25, 26, 27 and 28 are positioned on opposite sides of the tow 12 from the ducts 22, 22a, 23 and 23a so that the heated air flows through the tow to uniformly anneal all of the fibers therein.

The air from the ducts 24 and 24a of the first stage flows between a pair of spaced (flat bafiles 29 and 30 which are integral with plates 20 and 21 secured to the upper and lower sections respectively. The upper and lower bafiies 29 and 30, which define a nozzle or throat 31 through which the tow 12 passes, are provided with diverging portions 29a and 30a, respectively. The plates 20 and 21 are cut away (FIGURE 3) to provide openings from the exhaust ducts 25-28 to the third stage.

Since the cross sectional area of the throat 31 is fairly small, the air passes through this throat at a very high velocity. This moving air urges the tow through the heating chamber but does not have the positive feed that a pair of rolls would have. Therefore the filaments in the tow 12 are free to shrink or contract to the maximum possible extent beyond the throat 31. The rolls 10 feed the tow 12 to the chamber at the speed that the tow will be advanced by the air stream flowing through the throat or nozzle 31, so that there is substantially no tension in the tow advancing to the chamber 13. The rolls 11 are driven at a slower speed than are the rolls 10. This allows the filaments in the tow to shrink.

The first stage of the lower chamber section 15 is provided with partitions 36 and 37 which are positioned paral lel to and on opposite sides of the tow 12 to thereby provide side chambers for the withdrawal of air from the exhaust ducts 2'7 and 28. The partitions 36 and 37 are cut away at the ends of the exhaust ducts 27 and 28 so that these ducts are in communication with the side chambers. This is best shown in FIGURE 3.

Curved plates 38 in the side chambers lead from the exhaust duct 27 to the plate 21, the plate 21 being cut away to allow air flowing from the duct 27 to pass between the plate 38 and the floor of the chamber section 15 and then flow into the third stage in parallel with the air passing through the throat 31.

Plates 39 positioned in the side chambers lead from the exhaust duct 28 to the plate 21 to form exhaust passageways for air from the duct 28. As described above the partitions 36 and 37 are cut away at the ends of the duct 28 to allow air to flow from this duct into the space between the plates 38 and 39. Likewise, the plate 21 is cut away so that this air can flow directly from the exhaust duct 28, between the plates 38 and 39 and into the third stage.

0 FIGURE 3 and the above description explain the exhaust duct structure of the lower chamber section 15. The exhaust duct structure of the upper section 14 is of like nature.

Deflectors 32 and 33 in the third stage of the upper and lower section divert the air toward exhaust ducts 34 and 35 mounted on the upper and lower sections 14 and 15. A fan 40 driven by motor 41 draws air from a heating chamber 42 and directs it through ducts 18 and 19 into the first stage of the chamber 13. The air exhausted through the ducts 34 and 35 is directed back through a duct 43 to the heater 42. The ducts 19 and 34 are provided with a joints 46 and 47 so that the upper section 14 can be pivoted up and away from the lower section for lacing up the apparatus and for cleaning and maintenance.

' In operation of the apparatus, the rolls 10 advance the tow 12 to the chamber 13 and the rolls 11 carry it away. The fan 40 moves heated air through the ducts 18 and 19 into the first stage of the treating chamber; In this stage the heated air alternately impinges on opposite sides of the moving tow 12 as described above. The heated air passes through the tow and is carried by the exhaust ducts 28 to the third stage, except for the air moving through the ducts 24 and 24a. The air flowing through the ducts 24 and 24a passes through the throat 31 at a high velocity. This carries the tow into the third stage where air is stripped from the tow and the rolls 11 remove it. The deflectors 32- and 33 direct the stream of air from the throat 31 toward the ducts 34 and 35.

Air leakage into and out of the annealing chamber 13 can be controlled by valves 50 and 51. When valve 50, on the inlet or suction side of the fan 40, is opened and valve 51 is closed additional air is drawn into the closed circulation system through the valve 50. This air must be purged since the quantity of air inthe system cannot increase; A quantity, of air equal to that drawn in through valve 50 is expelled through the space between section 14 and 15 where the tow enters and leaves the annealing chamber 13. The effect of this is to scrub ambient air from the tow and insure a more uniform heating of the tow while it is in the annealing chamber 13. Contrariwise, if valve 50 is closed and valve 51 is opened, heated air will be purged through the open valve 51. The annealing chamber 13 is in a lower pressure section of the system than is valve 51 so that the amount of air purged through valve 51 is made up by entry of an equal amount of ambient air through. the openings in the annealing chamber 13 through which the tow 12 passes.

This condition may produce some nonuniformity in annealing which may be of use in novelty effects; The former condition, with valve opened and valve 51 closed, is the more desirable condition for most purposes. In addition to more uniform annealing, the purging of air from the system prevents a build-up of moisture and vapor in the annealing system.

It is to be understood that the embodiment of the invention disclosed herein may be modified or amended and that numerous other embodiments may be contemplated which will fall within the spirit and scope of the invention.

What is claimed is:

Apparatus for annealing a tow; comprising a pair of chamber sections positioned in facing relationship to define a tow path therebetween; means adjacent to the chamber sections for advancing a tow in one direction along said path; first means inthe chamber sections for directing heated air against and through the tow; a pair of plates mounted in the chamber sections in series with the first means; said plates having curved ends defining a throat through which heated air lifts and carries the tow; second means connected in series with the throat for carrying air away from the chamber sections; a duct interconnecting the first and second means to form a closed loop for the circulation of air; means in the duct for heating the air and means in the duct for forcing air around the closed loop in a direction such that a portion of the air flows in series through the firs-t means and throat, and then through the second means in that order and the remainder of the air flows directly from the first means to the third means in parallel with the air flowing through the throat, said tow and said air being passed through the chamber sections in the same direction.

References (Iited by the Examiner UNITED STATES PATENTS 559,498 5/1896 Scharrer 34-160 X 2,012,115 8/1935 Woodrufi 34160 2,065,032 12/1936 Spooner 34l22 2,144,919 1/1939 Gautreau 34--156 X 2,225,505 12/1940 Often 34-160 X 2,351,549 6/1944 Schwartz 34160 X WILLIAM F. ODEA, Acting Primary Examiner.

CHARLES A. CONNELL, NORMAN YUDKOFF,

Examiners. 

